Recent Posts

Monday, October 27, 2014

How to Repot an Orchid

Yes, you can do this. It's not rocket science. Repotting is fun. And your orchid will thank you, especially if it's been two or more years since it was repotted. Never repotted an orchid before? We can fix that. Come on into our greenhouse and I'll show you how.

1. Gather your materials.  A good basic orchid mix consists of equal parts fir bark, charcoal and sponge rock (aka coarse perlite). You can buy these products online from OFE International and Tropical Plant Products. They also sell high quality ready-to-use packaged orchid mixes. Grower's Tip: The organic component -in this case the bark- can make or break the quality of an orchid mix, because that's the part that breaks down with repeated watering. The bark should be Douglas Fir or Pinus radiata, and should be mold-free. Pinus radiata (sold as Orchiata) and kiln-dried Douglas Fir bark (sold as Rexius bark) last longer than regular Douglas Fir bark. Fir bark often needs to be rinsed beforehand in order to remove dust and sediment.

2. Select a plant. The best time to repot an orchid like Cattleya is when the new shoot is about the length of your pinkie finger. The new shoot indicates that the plant has started a new cycle of growth, the perfect time to provide new roots with fresh medium. We repot every two years, because that's the lifetime of fir bark mixes in our greenhouse. Any longer is asking for trouble -a waterlogged mix that kills roots. Grower's Tip: Keep your eye on that new shoot while repotting! It is as fragile as new asparagus and if you break it, you lose an entire season's growth, including the flowers.

3. Invert the plant, tap the rim of the pot against the table and remove the plant. Keep the new shoot well away from the table when you do this. Grower's Tip: Water your plant the day before to make it easier to dislodge.

4. Remove the old mix. Hold the plant by the pseudobulbs (not the roots!) with one hand and gently prod the mix with your other hand in order to loosen it. Grower's Tip: Expect to find new yellow-tipped roots emerging near the base of the new shoot. Be careful not to break them.

5. Remove the dead roots. Healthy roots are white and firm. Dead roots are grey/black and squishy. You can use pruners for cutting, but remember that viruses in plant sap can be spread by using the same tool on consecutive plants. Grower's Tip: That's why we use one razor blade per plant. We wrap used blades in duct tape before discarding them. When I divide a large plant, I use a kitchen knife and sterilize it with a propane torch between plants. Grower's Tip #2: Notice the new shoot face up on the table? Don't rest the plant on its new shoot. Grower's Tip #3: Orchid roots can absorb tannins from the bark in the mix and appear brown on the surface. A brown root can be healthy. When in doubt, cut a cross section--a healthy root will have a white core.

6. Wash the roots. I like to do this under a gentle stream of water at the sink. It gently removes the old bark hiding in inaccessible places. And it often reveals more dead roots that need to be cut away. If the roots are healthy you don't need to remove all the mix --only about three quarters. If the roots are in poor shape, remove as much old mix as possible. Grower's Tip: This is a great time to observe how your plant is constructed. Notice how the vertical shoots (the pseudobulbs) are connected by a horizontal stem (or rhizome, pronounced rye-zome). This will become important in a few minutes.

7. Choose a pot size based on the size of the root mass, not the top growth. One inch bigger all around is plenty. Orchids like to attach their roots to their surroundings. Let them. Grower's Tip: A step up in pot size isn't always necessary. Sometimes fresh mix and a clean pot of the same size is all that's needed.

8. Center the new shoot in the pot. See how I'm holding the older part of the plant against the rim of the pot? That's because I want the new shoot in the center where it will have plenty of room to grow over the next two years. Looks asymmetric, right? Absolutely. The new shoot goes in the center. Hold the base of the new shoot about a half inch below the top rim. That's your imaginary fill line.

9. While holding the plant in place with your left hand, add mix with your right hand, small amounts at a time.




Wednesday, October 8, 2014

Stanhopea connata

Stanhopea connata ABG# 1993-2450
Not every Stanhopea smells like a pastry shop. Poor Stanhopea connata. It's the one Stanhopea that can clear a room.
Dorsal view of Stanhopea connata ABG# 1993-2450
While most stanhopeas have fragrances delectable enough to eat, Stanhopea connata exudes cresole and indole. Cresole is the fragrance compound associated with coal tar (think freshly poured asphalt). And indole has a fragrance described in botanical literature as fecal. I was not, to be honest, in a hurry to have a closed door photo session with Stanhopea connata.
Front view of Stanhopea connata
And that's too bad! Look at that face, with the bold tiger stripes and spots. I was completely charmed. Charmed and overwhelmed, actually.
Dorsal view of the lip and column with sepals and lateral petals removed 
Of course, it doesn't matter one bit what I think of the fragrance. The fragrance is all about attracting a pollinator. And it's kind of cool to think that there are fragrance-collecting bee species in the tropics who are mad for asphalt and cow dung.
Dorsal view of the lip without the column
My photo shoot with S. connata lasted about an hour. Over time, the cresole seemed to diminish and the indole began to assert itself. But by the end I hardly noticed. What a handsome plant this is. The images will be stored in ABG's image library.
Ventral view of the lip
Stanhopea connata grows as an epiphyte along the eastern cordillera in Peru, Colombia and Ecuador. It is pollinated by Eulaema speciosa.
Ventral view of the column

Saturday, October 4, 2014

How to Repot Stanhopea

September and October are Stanhopea repotting season for us. Every grower has their own repotting technique, but I thought you might want to take a look behind the scenes at ours.

Orchids that are flourishing don't generally appreciate the root disturbance that repotting can inflict. Stanhopeas are no exception. We repot when: 1) The plant has overgrown the pot; 2) The medium needs to be replaced, either because it has deteriorated -after about two years- or because it is inappropriate for our growing conditions; or  3) The plant is in trouble. Signs of trouble include desiccated leaves and shriveled or rotting pseudobulbs.

The stanhopeas above, which we received last week from Andy's Orchids, fall into the second category. Andy grows his stanhopeas in a medium that works well for him, but turns to mush in our greenhouses during our hot & humid summers.

We repot our orchids when the new roots and shoots appear. For most stanhopeas, that's in late summer and early fall. In the photo above, you can see the new shoot on the Stanhopea graveolens in the foreground. Now is the time!

Because our plants are far from the main potting bench in the headhouse, I set up a temporary potting bench in our back-up greenhouse. It's just a pair of plastic sawhorses supporting a 5' rectangle of plywood. Potting materials include net baskets, razor blades and one of our favorite orchid media, a mixture of long-fibered premium moss and coarse tree fern fiber. The plants were watered the previous day in order to soften the potting medium.

1. To remove the plant, invert the pot and tap the rim against the edge of the potting bench.

2. Gently remove the old medium around the exterior of the root mass, small bits at a time so as to not break the new roots.

To remove the old medium from the center of the root mass, hold the plant by the pseudobulbs (not by the roots!), and wash the roots gently under running water. Remove about three quarters of the medium. It's not necessary to remove every bit unless you see rotting tissue. Rotting roots and pseudobulbs are easy to see after washing and can be removed with a razor blade.

3. Choose a pot size based on the size of the root mass. For a plant this size, we want a pot about an inch wider than the root mass on all sides. And, for a Stanhopea, choose a basket with openings that allow the downward-growing spikes to emerge from the root mass.

Friday, September 26, 2014

Deconstructing ruckeri

Side view of Stanhopea ruckeri 'Tikal' ABG# 1997-0230
A Stanhopea flower is an exquisite thing, but trying to observe one from every angle while it's still on the inflorescence is a frustrating experience because of the compact arrangement of flowers. It's especially hard to get a direct look at the upper surface of the lip because the column blocks its view. The best way to look at Stanhopea flower is to remove it and take it apart.

Dorsal view of Stanhopea ruckeri 'Tikal' ABG# 1997-0230
Dorsal view of the column and lip without the two lateral petals and three sepals
Dorsal view of the lip without the column
Ventral view of the lip
Ventral view of the column
Dissecting these flowers increases my admiration for them. And the powerful fragrance that is released inside our small closed library is wonderful. Some of them (like Stanhopea embreei, 99% trans-methylcinnamate) I want to inhale over and over again. How exactly do the Euglossine bees experience this fragrance, I wonder?

Tuesday, September 23, 2014

Two Stanhopea ruckeri Clones

Stanhopea ruckeri flowers in August and September in our greenhouses. It has been fascinating to observe the different color forms and scent variations among our plants. S. ruckeri varies in color from albino to apricot, and may occur with or without eyespots and scattered dots. Some clones have a scent that is almost undetectable. Others have a light floral fragrance. Still others smell like candy Red Hots. The morphology of their flowers is pretty similar. The biggest obvious difference is their scent chemistry.

The first two pictures show ABG# 1990-1503, a clone with lots of spots on the petals and sepals and two barely visible eyespots on the dorsal side of the hypochile. It has a light rosy floral fragrance whose main component is phenyl-ethylalcohol.

On the underside of # 1990-1503's lip are two more faint eyespots.

Another plant, # 1997-0230, has two bold eyespots. This clone smells like cinnamon (it's a mixture of trans-cinnamaldehyde, cinnamyl-alcohol and cinnamyl-acetate) and benzylaldehyde.

This plant also has a second pair of pale eyespots on the underside of the lip.

The extra sprinkling of tiny spots on the underside of the column were a surprise. The spots and the fragrances remind me that pollinators experience a sensory world very different from ours.

Stanhopea ruckeri, with its different chemotypes, is a puzzling entity. Calaway Dodson suggested that S. ruckeri may be a group of natural hybrids between S. wardii and S. oculata, but more research is needed.

We grow our plants in a mixture of long-fibered premium sphagnum and coarse chopped tree fern fiber. Stanhopea ruckeri is easy to grow in an intermediate (58º night minimum) temperature greenhouse and 60% shade. It grows quickly, produces multiple spikes and makes a handsome overwhelmingly fragrant specimen basket.

Friday, September 19, 2014

Stanhopea Season 2014

Stanhopea oculata ABG# 96-0801 flower, lateral view
Lots of activity buzzing around our Stanhopea collection this summer. Last year's newly divided plants are now big enough to carry capsules, so I've been busy pollinating our plants. In addition, photographic documentation of our collection is now possible with a newly developed image library that references our plant records database. (Thanks Michael Wenzel and Cindy Jeness: you guys are terrific!) So I have also started systematically photographing each Stanhopea accession.

Stanhopea oculata ABG# 96-0801 flower
For each accession, there will be six images that show morphological features that are diagnostic for Stanhopea. When an identification needs verifying, like this one, I send the images to Dr. Mark Whitten and Dr. Günter Gerlach.

Stanhopea oculata ABG# 96-0801 lip and column
As I learned from them, it's not always easy to put a name on a Stanhopea. The plant pictured here, which we received as Stanhopea oculata, is a good example. It has features in common with S. oculata, S. whittenii and S. dodsoniana. Which is it? S. oculata  varies enormously in the size and morphology of its flowers over its wide range (Mexico to Venezuela). Its fragrance is similar to several other morphologically similar species with whom it shares pollinators, making the existence of natural hybrids within populations likely. In fact, Rudolf Jenny states that S. oculata populations frequently consist of a mixture of both of the parents, natural hybrids, and back-crosses. So, is Stanhopea oculata five new species with some shared characteristics? Or do we treat it as one widespread species complex on its way to becoming new distinct species? What is Stanhopea oculata? And what the heck do I write on this plant's label?

Stanhopea oculata ABG# 96-0801 lip without column, dorsal view
Right now, there's not a good answer to these questions other than 'more work needs to be done.' For now our plant's identity remains as we received it: Stanhopea oculata ABG# 96-0801.
Stanhopea oculata ABG# 96-0801 lip, ventral view
In spite of the taxonomic uncertainty, I'm having a blast. Typically, I use the oldest flower on the inflorescence as the capsule parent and the youngest flower for dissection. Dissecting them inspires awe and admiration. These plants are so beautiful. It's a privilege to do be able to document them.
Stanhopea oculata ABG# 96-0801 column, ventral view

Friday, September 12, 2014

Paphiopedilum dayanum

That fringe of long silky hairs. Paphiopedilum dayanum always gets a second look from me. True, there are other Paphs with hairs, but this is the only one in our collection that triggers a grooming impulse. What other orchid has petals that need combing?

Paphiopedilum dayanum is one of those select plants that grows on Borneo's Mt. Kinabalu and nowhere else. Like many terrestrial orchids it occupies a specialized micro-habitat. Phillip Cribb reports that it grows in leaf litter under bamboo and at the base of trees on steep ridges around the mountain at 300 to 1450 meters elevation.

Why the the hairs on the petals? They may be an adaptation to attract flies that can pollinate the flowers. Hairs, warts, aphid-like bumps. Carrion colored flowers. Together, these comprise a syndrome associated with fly pollination.

Paphiopedilum dayanum has been trouble-free for us. It seems fine with temperatures on the warm side of intermediate (60 to 62º night minimum) in a shady greenhouse in a mixture of fine fir bark, chopped moss, charcoal and perlite.


Thursday, September 11, 2014

Lycaste schilleriana var. rosea

Among all of our Lycaste species, this could be my favorite. Of the two or three dozen Lycaste species in cultivation, most fall within the traditional spring floral color spectrum--pinks, yellows, whites. Not this one.

This is Lycaste schilleriana var. rosea. I love the deep olive green of the sepals. They are olive on the exterior and bronze on the inside.

Even more remarkable is the extraordinary length of its sepals. Each sepal is about 3 inches long, giving L. schilleriana the widest flowers in the genus.

The buds look like elongated beaks.

Lycaste schilleriana var. rosea likes a greenhouse at the cool end of the intermediate temperature spectrum. For now, our plant resides in our shadiest most humid greenhouse right next to the wet wall, where the summer daytime temperature maxes out at about 83º. If the current warming trend continues, we may have to move it to the Tropical High Elevation House.

Lycastes are pollinated by Euglossine bees. Lycaste schilleriana is known from Panama and Colombia where it grows as a lithophyte at around 1400 meters elevation.
Related Posts Plugin for WordPress, Blogger...